The paper “Creation of discontinuities in circle maps“, co-authored by Gianne Derks, Paul Glendinning (Manchester), and Anne Skeldon, has been published this week in Proceedings A of the Royal Society of London (link here). Motivated by circle maps arising in biology, the paper studies the transitions in circle maps that occur near the creation of a discontinuity. At the transition, the associated maps have square root singularities and the paper analyses the generic properties of such maps with gaps, showing how border collisions and saddle-node bifurcations are interspersed. The image below shows Figure 10 from the paper.
![](https://blogs.surrey.ac.uk/mathsresearch/wp-content/uploads/sites/11/2021/07/rspa20200872f10-1.jpg)